Concentric circle dimensions

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jmaustpc
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Re: Concentric circle dimensions

Post by jmaustpc »

papyblaise wrote: Mon Nov 23, 2020 2:53 pm
that is not right, you can not apply a tangent between a point and the circle edge in sketcher. You would use "point on object" constraint.
What is your remark :?:
I place the point on the circle, then I made this point tangent to the OX axis, and the proof by the image is correct :!:
You can not make a point tangent to X axis (nor to a circle's edge), that makes no sense and FreeCAD will not do it. Nothing in your imagine appears to be Tangent to anything.


you said
papyblaise wrote: Mon Nov 23, 2020 11:56 am or you place a point on each circle tangent to the circles and to an axis line
that does not make any sense.

You appear to have used "point on object" constraint. But you say "Tangent", perhaps you don't know what Tangent means in English, perhaps its your trying to translate ... I don't know, but what you said is nonsense.
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MisterMaker
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Re: Concentric circle dimensions

Post by MisterMaker »

I am guessing the reason people here want to know if it's a constrain or dimension is the place it in a category?
For me as an more end user it doesn't matter You should be able to place a dimension or constrain between 2 circles in both categories.

I do think it is more important in constrains, since offsetting a circle is something that is used in a lot of designs.
The drawing is not that important. Although I normally imported my constrains into my drawing, I did that in Solidworks.
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papyblaise
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Re: Concentric circle dimensions

Post by papyblaise »

nonsens yourself , how you tell the constraints picture dot#2 and the others picture dot#3
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dot#2.PNG
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dot#3.PNG
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papyblaise
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Re: Concentric circle dimensions

Post by papyblaise »

You should be able to place a dimension or constrain between 2 circles in both categories
yes surely, but how Fc will be able to choose the shortest distance between the 2 circles
in my picture dot # 2 you can measure the distance between the 2 points but it is not the shortest between the circles
to get there you must have the 2 points aligned on a radius, which is why I chose the simplest: one of the axes (OX)
jmaustpc
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Re: Concentric circle dimensions

Post by jmaustpc »

papyblaise wrote: Mon Nov 23, 2020 3:43 pm nonsens yourself , how you tell the constraints picture dot#2 and the others picture dot#3
Are you for real? You said "Tangent", your pictures do not show anything being "Tangent", they do show "point on object" constraint but not "Tangent". Hence what you are saying about "tangent" makes no sense.
MisterMaker wrote: Mon Nov 23, 2020 3:39 pm constrain or dimension
Constraints in sketcher, you do it in the ways we said here, not a direct tool.

Dimension in TechDraw 2d Drawing, then yes you can do that already. Here is a demo...
Screenshot_20201124_025445.png
Screenshot_20201124_025445.png (35.17 KiB) Viewed 1454 times

You can not import Sketcher constraints directly into a TechDraw 2d drawing in FreeCAD.

The TechDraw dimensions can be derived from the drawing in ways that were not specified directly by a sketcher constraint. They can also be directly linked to geometry on a solid in your main window.

As far as I know, no one is working on implementing importing Sketcher Constraints, but that does not mean someone can't, I think for myself it is low priority because it is easy to work around but if you can write the code or find someone else to write the code, no doubt in principle it could be accepted.
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papyblaise
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Re: Concentric circle dimensions

Post by papyblaise »

you want whatever we give you the point for the benefit of the doubt :?:
ok I give it you :!:
you tire me :!:
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papyblaise
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Re: Concentric circle dimensions

Post by papyblaise »

but i don't like to lose
this faith is indeed a tagence , isn't it
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chrisb
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Re: Concentric circle dimensions

Post by chrisb »

May I jump in?
This icon creates a point-on-object constraint: Image.
This icon creates a tangent constraint: Image

Both have in common that the icon has an arc and something else. Trying to add a point to a circle results in an error.
(the size of the image is unintended huge, due to high resolution of display - sorry.)
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Bildschirmfoto 2020-11-23 um 18.00.47.png
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A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
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watsug
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Re: Concentric circle dimensions

Post by watsug »

jmaustpc wrote: Mon Nov 23, 2020 12:27 pm no, this topic is about constraining a radius with a constraint, one specific set of constraints are described as dimensional constraints but not all and even those are still constraints that constrain geometry.

To put it simply, a dimension object/tool in FreeCAD reads a value from something, the constraint forces something to have a value or do something else of a non-numerical value, like tangent etc. Depending on context a dimension could be an aspect of an item e.g. a line length could described as its dimension, but something else creates or forces that dimension (a property, a constraint, etc.).
Thanks for writing the explanation! So dimensional constraint is a subset of constraint, that has a value. Is it possible to have a dimensional constraint without a value?

If you look in the picture in the op, it is clear that they want to put a dimensional constraint of the difference in size of the circle. Or is this not a dimensional constraint? As a user (without regard how the Sketcher is programmed or works under the hood, I don't know) I also find it would be useful to be able to add a distance/offset of circle lines in a more simple way. (I understand if this isn't something that is prioritized)
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papyblaise
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Re: Concentric circle dimensions

Post by papyblaise »

This icon creates a point-on-object constraint: Image.
This icon creates a tangent constraint:
yes I mistaque :oops:
Trying to add a point to a circle results in an error
are you sure ... how I had doing ... :?:
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